For example, an IC (Integrated Circuit) system is widely known as a system for performing short-range communication. In an IC card system, a so-called RF (Radio Frequency) field is formed such that a reader/writer generates electromagnetic waves. When an IC card is brought close to the reader/writer, the IC card is supplied with power through electromagnetic induction and performs data transfer between it and the reader/writer (see, for example, Japanese Unexamined Patent Application Publication No. 10-13312).
Presently implemented specifications of IC card systems include, for example, those called Type A, Type B, and Type C.
Type A is employed as the MIFARE method of Philips. For data transmission from a reader/writer to an IC card, Miller-based data encoding is performed. For data transmission from an IC card to a reader/writer, Manchester-based data encoding is performed. Also, in Type A, 106 kbps (kilo bit per second) is employed as a data transfer rate.
In Type B, for data transmission from a reader/writer to an IC card, data encoding based on NRZ is performed, while, for data transmission from an IC card to a reader/writer, data encoding based on NRZ-L is performed. Also, in Type B, 106 kbps is employed as a data transfer rate.
Type C is employed as the Felica method of Sony Corporation, the present Applicant. For data transmission from a reader/writer to an IC card, Manchester-based data encoding is performed. In Type C, 212 kbps is employed as a data transfer rate.
Accordingly, when considering, for example, the transfer rates, Types A (or B) and C differ in transfer rate. Thus, use of an IC card based on the other type in a service in which Type A or C is employed is difficult since users may become confused, etc.
Also, it is expected that IC card systems enabling data transmission at, for example, 424 kbps and 848 kbps will appear. In such a case, it is required that compatibility with the existing IC card system be achieved.
In addition, conventionally, a reader/writer transmits data to an IC card by modulating (a carrier corresponding to) electromagnetic waves generated by the reader/writer, and the IC card transmits data to the reader/writer by performing load modulation on (a carrier corresponding to) electromagnetic waves generated by the IC card. Thus, even if IC cards exchange data, it is required that a reader/writer be provided therebetween.
However, from now, it is expected that the need for IC cards themselves to generate electromagnetic waves and to directly exchange data will increase.